AddRequestHeader plug-in - Alibaba Cloud Service Mesh - Alibaba Cloud Documentation Center

You can configure the AddRequestHeader plug-in to add the information of the request header to the response header when a specific HTTP status code is returned.

Prerequisites

Automatic sidecar proxy injection is enabled.
An ingress gateway is deployed. For more information, see Create an ingress gateway.
Deploy the sleep service and HTTPBin service in the data plane cluster. For more information, see Deploy the HTTPBin application.

Configuration fields

Name

Data type

Required

Default value

Description

status_codes

String, array

Yes

Specifies a specific set of HTTP status codes, including 200, 404, and503. When these codes are returned, response header contains the information about request header.

patch_context

String

Yes

Specifies the scope in which the plug-in takes effect. Valid values:

GATEWAY: The plug-in only takes effect on the gateway.
ANY: The plug-in takes effect on both the gateway and the sidecar proxy.

Sample configuration

ASM gateway returns request header when the request is successful

In this example, set plug-in parameters as follows to enable the gateway to display the information about request header in the response header when the request is successful (The HTTP status code 200 is returned).

status_codes: 
  - "200"
patch_context: GATEWAY

Set the Plug-in Effective Scope to Gateway Scope, and select ingressgateway.

HTTP status code 200 is returned.

curl -H "user: test" -I {gateway IP address}/status/200

Expected output:

HTTP/1.1 200 OK
host: 121.40.XXX.XX
server: istio-envoy
date: Thu, 16 Jun 2022 07:58:05 GMT
content-type: text/html; charset=utf-8
access-control-allow-origin: *
access-control-allow-credentials: true
content-length: 0
x-envoy-upstream-service-time: 2
accept: */*
user: test
x-forwarded-for: 10.0.0.130
x-forwarded-proto: http
x-envoy-internal: true
x-request-id: 4e284975-fa1d-41c4-9676-9785c83e7385
user-agent: curl/7.79.1

The result shows that the response header contains a custom request header user: test when the gateway returns an HTTP status code 200.

HTTP status code 400 is returned.

curl -H "user: test" -I {gateway IP address}/status/400

Expected output:

HTTP/1.1 400 Bad Request
server: istio-envoy
date: Thu, 16 Jun 2022 07:58:09 GMT
content-type: text/html; charset=utf-8
access-control-allow-origin: *
access-control-allow-credentials: true
content-length: 0
x-envoy-upstream-service-time: 9

The result shows that the response header contains no request header when the gateway returns an HTTP status code 400.

Configure request header information to be returned when a specific service returns an HTTP status code 400

AddRequestHeader plug-in can take effect on any specified service. In this case, you need to set the patch_context parameter to ANY. Configure the plug-in as follows:

status_codes: 
  - "400"
  - "503"
patch_context: ANY

You can set the status_codes parameter to any common error codes. Set the Plug-in Effective scope to Workload Scope, and select httpbin service in the default namespace. Run the following command to directly initiate a request to an httpbin service through a sleep service.

kubectl exec -it deploy/sleep -- curl -H "user: test" -I httpbin:8000/status/400

Expected output:

HTTP/1.1 400 Bad Request
host: httpbin:8000
server: envoy
date: Thu, 16 Jun 2022 08:**:** GMT
content-type: text/html; charset=utf-8
access-control-allow-origin: *
access-control-allow-credentials: true
content-length: 0
x-envoy-upstream-service-time: 13
accept: */*
user: test
x-forwarded-proto: http
x-request-id: 1780766e-8273-4703-8902-6a513eb6bcfc
x-envoy-attempt-count: 1
x-forwarded-client-cert: By=spiffe://cluster.local/ns/default/sa/httpbin;Hash=bb3ab9200f3ce3e1b53493ddf701838d6d3538167ff6613d2ec319d4872c8966;Subject="";URI=spiffe://cluster.local/ns/default/sa/sleep
user-agent: curl/7.83.1-DEV

The result shows that the response header contains a custom request header user: test when the HTTPBin service returns an HTTP status code 400.